Acanthornis magnus greenianus (Scrubtit (King Island))

Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Scientific name, common name (where appropriate), major taxon group

Acanthornis magnus greenianus (Scrubtit (King Island))

2. National Context

Scrubtit (King Island) is endemic to King Island, Tasmania. It is not listed under the EPBC Act or Tasmanian legislation.

3. How judged by TSSC in relation to the EPBC Act criteria.

TSSC judges the species to be eligible for listing as critically endangered under the EPBC Act. The justification against the criteria is as follows:

Criterion 1 - Decline in numbers

Formerly, Scrubtit (King Island) probably existed as a single population across the island, but is now restricted in range to a few habitat remnants and approximately 200 mature individuals. Recently collected birds have been affected by large numbers of ticks which experts consider may be contributing to the decline in the number of mature individuals. However, there are no quantitative data available on rates of decline against this criterion.

Therefore, the species is not eligible for listing under this criterion.

Criterion 2 - Geographic distribution

Scrubtit (King Island) is restricted to King Island, Tasmania. Formerly, it probably existed as a single population across the island, but is now restricted in range to a few habitat remnants and approximately 200 mature individuals. Its geographic distribution is very restricted, the area of occupancy being 5km2. The population is considered to be severely fragmented, comprising an estimated four sub-populations, the largest containing 50 mature individuals. Continuing declines in the extent of occurrence, area of occupancy and number of breeding birds are expected. The area of suitable habitat on King Island has been reduced by land clearance, and recently collected birds have been affected by large numbers of ticks which experts consider may be contributing to the decline in the number of mature individuals.

Therefore, the species is eligible for listing as critically endangered under this criterion.

Criterion 3 - Population size and decline in numbers or distribution

The number of mature individuals is estimated to be approximately 200 , which is very low. The rate of decline in population numbers has not been quantified, however, the number of mature individuals is likely to continue to decline, possibly due to tick infestation. The population is also considered to be severely fragmented with no population containing more than 50 mature individuals. In conjunction with the low population numbers, the geographic distribution is precarious for its survival.

Therefore, the species is eligible for listing as critically endangered under this criterion.

Criterion 4 - Population size

The number of mature individuals (breeding birds) is estimated to be approximately 200.

Therefore, the species is eligible for listing as endangered under this criterion.

Criterion 5 - Probability of extinction in the wild

There is no quantitative data available against this criterion.

4. Conclusion

Based on information in the Action Plan for Australian Birds, the geographic distribution of Scrubtit (King Island) is very restricted, the area of occupancy being 5km2. The population is considered to be severely fragmented, comprising four sub-populations, the largest containing 50 mature individuals. Continuing declines in the extent of occurrence, area of occupancy and number of breeding birds are expected. The area of suitable habitat on King Island has been reduced by land clearance and recently collected birds have been affected by large numbers of ticks which experts consider may be contributing to the decline in the number of mature individuals. The number of mature individuals is estimated to be approximately 200, which is very low and the number is likely to continue to decline and its geographic distribution is precarious for its survival.

The species is eligible for listing as critically endangered under criteria 2 and 3.

5. Recommendation

TSSC recommends that the list referred to in section 178 of the EPBC Act be amended by including in the list in the critically endangered category:

Acanthornis magnus greenianus Scrubtit (King Island)